title: Organelles contribute differentially to reactive oxygen species-related events during extended darkness.
abstract: Treatment of Arabidopsis (Arabidopsis thaliana) leaves by extended darkness generates a genetically activated senescence program that culminates in cell death. The transcriptome of leaves subjected to extended darkness was found to contain a variety of reactive oxygen species (ROS)-specific signatures. The levels of transcripts constituting the transcriptome footprints of chloroplasts and cytoplasm ROS stresses decreased in leaves, as early as the second day of darkness. In contrast, an increase was detected in transcripts associated with mitochondrial and peroxisomal ROS stresses. The sequential changes in the redox state of the organelles during darkness were examined by redox-sensitive green fluorescent protein probes (roGFP) that were targeted to specific organelles. In plastids, roGFP showed a decreased level of oxidation as early as the first day of darkness, followed by a gradual increase to starting levels. However, in mitochondria, the level of oxidation of roGFP rapidly increased as early as the first day of darkness, followed by an increase in the peroxisomal level of oxidation of roGFP on the second day. No changes in the probe oxidation were observed in the cytoplasm until the third day. The increase in mitochondrial roGFP degree of oxidation was abolished by sucrose treatment, implying that oxidation is caused by energy deprivation. The dynamic redox state visualized by roGFP probes and the analysis of microarray results are consistent with a scenario in which ROS stresses emanating from the mitochondria and peroxisomes occur early during darkness at a presymptomatic stage and jointly contribute to the senescence program.
authors.affiliation: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
authors.forename: Shilo
authors.initials: S
authors.lastname: Rosenwasser
authors.forename: Ilona
authors.initials: I
authors.lastname: Rot
authors.forename: Evelyn
authors.initials: E
authors.lastname: Sollner
authors.forename: Andreas J
authors.initials: AJ
authors.lastname: Meyer
authors.forename: Yoav
authors.initials: Y
authors.lastname: Smith
authors.forename: Noam
authors.initials: N
authors.lastname: Leviatan
authors.forename: Robert
authors.initials: R
authors.lastname: Fluhr
authors.forename: Haya
authors.initials: H
authors.lastname: Friedman
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D016923:Cell Death; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003624:Darkness; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins; D008928:Mitochondria / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D010084:Oxidation-Reduction; D020675:Peroxisomes / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology / Q000528:radiation effects; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D013312:Stress, Physiological; D059467:Transcriptome
chemical_list: D000975:Antioxidants; D029681:Arabidopsis Proteins; D017382:Reactive Oxygen Species; D002734:Chlorophyll; D049452:Green Fluorescent Proteins